This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-71525, filed on Mar. 15, 2002, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to an organic EL element, and to an organic EL display using the same.
2. Description of the Related Art
Organic EL elements have features such as spontaneous light emission, high-speed response, and the like, and they are expected to be applied to flat panel displays. A two-layer (laminated) organic thin film having positive hole transport properties (positive hole transporting layer) and organic thin film having electron transport properties (electron transporting layer) having electron transport properties has been reported (C. W. Tang and S. A. VanSlyke, Applied Physics Letters vol.51, p.913 (1987)), and due to its large area light-emitting element which emits light at a low voltage of 10V or less, it has recently been attracting attention. Organic EL elements of the laminated type have the basic construction, positive electrode/positive hole transporting layer/light-emitting layer/electron transporting layer/negative electrode, wherein the functions of the positive hole transporting layer or electron transporting layer may be added to that of the light-emitting layer as in the two-layer type.
It is expected that organic EL elements will soon be applied to full color displays. In this full color display, it is necessary to have pixels emitting light of three primary colors, blue (B), green (G) and red (R) arranged on the panels. There are three methods for achieving such arrangement;
(a) providing three types of organic EL elements, blue (B), green (G), red (R),
(b) separating the light emission light from an organic EL element emitting white light (which is a mixture of blue (B), green (G) and red (R) light) by color filters, and
(c) converting the light emission from an organic EL element emitting blue light into green (G) and red (R) light emission by a color conversion layer using fluorescent light.
In all of these systems, blue (B) light emission is indispensable.
Since the luminescence color in an organic EL element is determined by the unique excitation energy of the light-emitting molecule, in order to obtain blue (B) light emitting, a light-emitting molecule which has an excitation energy corresponding to the optical energy of blue light is needed. Moreover, in order to obtain a high quality full color display, the blue light emission organic EL element used for it must have high luminance, high efficiency and high color purity.
However, the characteristics of the blue light-emitting organic EL elements of the related art could not be said to have sufficient light-emitting luminance, light-emitting efficiency, color purity, and the like, hence further improvements were required.
It is therefore an object of the present invention to provide an organic EL element having excellent light-emitting efficiency, light-emitting luminance and color purity of blue light, and a highly efficient organic EL display using this organic EL element.
The organic EL element of the present invention comprises a specific 1,3,6,8-tetrasubstituted pyrene compound as light-emitting material.
An organic EL display of the present invention comprises an organic EL element of the present invention.